AD 87-11-08 R1

87-11-08 R1 AEROSPATIALE: Amendment 39-5628 as amended by amendment 39-5984. Applies to ATR-42 series airplanes, certificated in any category, unless the equivalent of Production Modification 1397 was installed prior to delivery.

Compliance is required as indicated, unless previously accomplished.

To prevent simultaneous loss of both pilots' primary attitude and heading information generated by Attitude and Heading Reference Systems (AHRS), accomplish the following:

A. Within 15 days after June 8, 1987 (the effective date of Amendment 39-5628, AD 87-11-08), accomplish the following:

1. Isolate the pilots' AHRS (AHRS Number 1) from the System Avionics Standard Communications Bus (ASCB) in accordance with Aerospatiale Service Bulletin ATR- 42-34A-0016, dated March 23, 1987, and ensure that Electronic Flight Instrument System (EFIS) Symbol Generators having part number 700544-411, Mod-level U or subsequent, have been installed.

2. Insert the following intothe Airplane Flight Manual (AFM) Limitations Section 2. This can be accomplished by inserting a copy of this AD into the AFM and into the Flight Crew Operations Manual (FCOM), if used.

a. "Disconnect autopilot at or above 200 feet above ground level (AGL)."

b. "Approach operations are limited to Category I or higher weather minima."

B. Replacement of the Attitude and Heading Reference Systems (AHRS) with a modified AHRS, and connection of four (4) wires between terminal blade 67VT1 and connector 1FP1-AA, in accordance with Aerospatiale Service Bulletin ATR42-34-340018, Revision 1, dated September 22, 1987, constitutes terminating action for the requirements of paragraph A., above.

C. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Standardization Branch, ANM-113, FAA, Northwest Mountain Region.

NOTE: The request should be forwarded through an FAAPrincipal Maintenance Inspector (PMI), who may add any comments and then send it to the Manager, Standardization Branch, ANM-113.

D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of the modifications required by this AD.

All persons affected by this directive who have not already received the appropriate service document from the manufacturer may obtain copies upon request to Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 03, France. This document may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington or the Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This Amendment 39-5984 amends AD 87-11-08, Amendment 39-5628.

This Amendment, 39-5984, becomes effective September 3, 1988.